1. Field
Exemplary embodiments relate to an electromagnetic coil system for driving control of a micro-robot, and more particularly to an electromagnetic coil system that structurally requires fewer electromagnetic coils compared to an existing electromagnetic coil system for which a pair of Helmholtz coils and a pair of Maxwell coils are required, so that it can reduce a size thereof to increase space efficiency and reduce power consumption thereof to increase power efficiency.
2. Description of the Related Art
In general, existing micro-robot electromagnetic driving systems are made up of an electromagnet coil using a Helmholtz coil and a Maxwell coil, and include a power amplifier capable of applying electric current to each coil and a controller capable of measuring and controlling a position of a micro-robot.
Here, the Helmholtz coil means that a pair of same circular coils are separated from each other by a distance corresponding to a winding radius and are disposed so that winding central axes of the two coils are identical with each other. Further, the Maxwell coil means that a pair of same circular coils are separated from each other by a distance corresponding to √{square root over (3)} times a winding radius and are disposed so that winding central axes of the two coils are identical with each other. Meanwhile, the micro-robot refers to a small movable object of several millimeters or less in which a permanent magnet is mounted.
FIG. 1 is a constituent diagram showing a conventional two-dimensional electromagnetic coil system.
As shown in FIG. 1, a conventional electromagnetic coil system is equipped with Helmholtz coils 205, 209, 215, and 219 and Maxwell coils 207, 211, 213, and 217. The Helmholtz coils generate a uniform strength of magnetic flux within a workspace of a micro-robot 229 located in the middle between the two coils in a direction in which winding centers of the two coils are connected. The pair of Maxwell coils generates magnetic flux whose strength is increased at a constant rate in the direction. Thereby, rotation and movement of the micro-robot 229 are possible.
To be specific, first, when the uniform strength of magnetic flux is generated within the workspace of the micro-robot 229 in a winding central axis direction of the coils by applying the electric currents to the pair of Helmholtz coils 205 and 209 in the same direction, rotational torque acts on the micro-robot 229 when an internal magnetization direction of the micro-robot 229 is different from a direction of the magnetic flux (here, a horizontal direction), and the micro-robot 229 rotates in place until the magnetization direction is identical with the magnetic flux direction.
Next, when the magnetic flux constantly increased in the coil winding central axis direction is generated by applying the same electric currents to the pair of Maxwell coils 207 and 211 located in parallel outside the Helmholtz coils 205 and 209 in opposite directions, the micro-robot 229 moves in a direction in which it is aligned by the Helmholtz coils 205 and 209. In this case, a rate of change of the magnetic flux based on a distance is adjusted using an intensity of the electric currents, each of which is applied to the Maxwell coils 207 and 211. Thereby, a propulsive force applied to the micro-robot 229 can be controlled. The micro-robot 229 can be controlled so as to be propelled in the opposite direction by inverting the direction in which the electric current is applied.
This constitution is expanded. That is, as shown in FIG. 1, the Helmholtz coils 205, 209, 215, and 219 and the Maxwell coils 207, 211, 213, and 217 are disposed in pairs in X and Y axis directions orthogonal to each other. Thereby, the micro-robot can be driven on a plane (XY plane) in an arbitrary direction and to an arbitrary position.
However, since the conventional electromagnetic coil system uses a total of four pairs of coils, i.e. two pairs of Helmholtz coils and two pairs of Maxwell coils, it has a disadvantage in that it has a large volume and a lot of power consumption. Further, due to this disadvantage, above all, in the application to a medical field, due to the large volume and the lot of power consumption of the two-dimensional electromagnetic coil system for controlling driving of the micro-robot compared to the workspace of the micro-robot, there is a problem in that the practical use of the system is reduced.